Portion Of Meniscus Research Articles

Reduction of in situ force through the meniscus with phased inner resection of medial meniscus: an experimental study in a porcine model

PurposePartial meniscectomy can cause osteoarthritic changes in knees, as inner portion as well as peripheral portion of meniscus is important. The hypothesis of this study was that the amount of the inner resection of medial meniscus affected the in situ forces through the meniscus and the tibial varus and external rotation under axial load.MethodsFourteen intact porcine knees were investigated with a six-degree of freedom robotic system and force/moment, and the three-dimensional path of intact knees were recorded by universal force sensor when an axial load of 300-N was applied at four different flexion angles (30°, 60°, 90°, and 120°). The same examination was performed on three phased inner resections (30%, 60%, and 90% width) of the medial meniscus. Finally, all paths were reproduced after total medial meniscectomy, and in situ forces of the medial meniscus were calculated based on the superposition principle. Changes in tibiofemoral varus/valgus and internal/external rotation alignment during an axial load were also calculated.ResultsIn situ forces of the medial meniscus decreased according to the amount of meniscal resection at all flexion angles. The reduction was significant in knees with inner resections of > 60% width at all flexion angles and even of 30% width at a flexion angle of 120° (p < .05). Incremental changes in the tibiofemoral varus alignment increased depending on the inner resection width at all flexion angles (p < .05).ConclusionThe amount of inner resection of the medial meniscus was related to reduction of its in situ forces and increment of the tibial varus rotation under axial load.

Improved arthroscopic one-piece excision technique for the treatment of symptomatic discoid medial meniscus

BackgroundDiscoid medial meniscus is an extremely rare abnormality of the knee. During arthroscopic meniscectomy for symptomatic discoid medial meniscus, it is difficult to remove the posterior portion of the meniscus because of the confined working space within the compartment and the obstruction caused by the anterior cruciate ligament and the tibial intercondylar eminence. To overcome these problems, we describe an improved arthroscopic technique for one-piece excision of symptomatic discoid medial meniscus through three unique portals.MethodsThree improved portals were made in the injured knee: a standard anteromedial portal, a central transpatellar tendon portal, and a high anterolateral portal. The anterior side of the discoid medial meniscus was cut 7 mm from the periphery of the meniscus. Next, the anterior portion of the free discoid meniscus fragment was pulled in the anterolateral direction with tension. A curve-shaped cut was made along the longitudinal tear to the posterior horn using basket forceps through the standard anteromedial portal. Then, the anterior portion of the free discoid meniscus was pulled in the anteromedial direction. Pulling the fragment under tension made it easier to cut the posterior side of the discoid meniscus. The posterior side of the discoid meniscus was cut 7 mm from the periphery of the meniscus with straight scissors or basket forceps through the central transpatellar tendon portal.ResultsThis technique resulted in satisfactory results. Excellent visualization of the posterior part of the discoid medial meniscus was gained during the procedure, and it was easy to cut the posterior part of the discoid medial meniscus. No recurrent symptoms were found.ConclusionsThis improved arthroscopic one-piece excision technique for the treatment of symptomatic discoid medial meniscus enables the posterior part of the meniscus to be cut satisfactorily. Moreover, compared with previous techniques, this novel technique causes less formation of foreign bodies and less damage to the anterior cruciate ligament, medial collateral ligament, and cartilage and requires a shorter procedural time.

The differences on extracellular matrix among each portion of meniscus

The differences on extracellular matrix among each portion of meniscus

Arthroscopic Split Transpositional Repair for Torn Complete Discoid Lateral Meniscus

A 20-year-old man presented with a 5-year history of pain in his left knee. He reported intermittent swelling and pain, especially after sporting activities. Arthroscopic surgery revealed that the entire anterior and mid-body of the discoid meniscus had been lost, and the remaining portion was shifted to posterocentral direction. Considering his age, resection of the entire meniscus was initially thought to be undesirable, although there was strong possibility of a re-tear. Although there was considerable anterocentral loss of the meniscus, the thickened inner portion of meniscus, which was displaced to the intercondylar notch, had remained relatively intact. Therefore, the lost part of the meniscus was reconstructed by transposing the remaining inner fragment. Margins of the torn side were freshened and abraded. The thick inner portion of remnant meniscus was reshaped by trimming the inferior portion. Subsequently, the posteromedial corner of remnant discoid meniscus was divided. The inner portion of the torn discoid meniscus was then flipped to the position of anterior and mid-body of the meniscus. The transposed portion was repaired using outside-in sutures and augmented with an exogenous blood clot. Surprisingly, follow-up magnetic resonance images at 40 months confirmed healing, and the patient was satisfied with the surgical outcome.

Meniscus structure in human, sheep, and rabbit for animal models of meniscus repair

Meniscus injury is a frequently encountered clinical orthopedic issue and is epidemiologically correlated to osteoarthritis. The development of new treatments for meniscus injury is intimately related to the appropriateness of animal models for their investigation. The purpose of this study was to structurally compare human menisci to sheep and rabbit menisci to generate pertinent animal models for meniscus repair. Menisci were analyzed histologically, immunohistochemically, and by environmental scanning electron microscopy (ESEM). In all species, collagen I appeared throughout most menisci, but was absent from the inner portion of the tip in some samples. Collagen II was present throughout the inner main meniscal body, while collagen VI was found in pericellular and perivascular regions. The glycosaminoglycan-rich inner portion of menisci was greater in area for rabbit and sheep compared to human. Cells were rounded in central regions and more fusiform at the surface, with rabbit being more cellular than sheep and human. Vascular penetration in rabbit was confined to the very outermost region (1% of meniscus length), while vessels penetrated deeper into sheep and human menisci (11-15%). ESEM revealed a lamellar collagenous structure at the articulating surfaces of sheep and human menisci that was absent in rabbit. Taken together, these data suggest that the main structural features that will influence meniscus repair-cellularity, vascularity, collagen structure-are similar in sheep and human but significantly different in rabbit, motivating the development of ovine meniscus repair models.